Pumping systems for the delivery of fluids intravenously or intra arterially are well known in the prior art and are in widespread daily use in hospitals throughout the world. These systems are commonly used for the intravenous or intra arterial delivery of such fluids as glucose solutions and blood plasma, and for the delivery of drugs, all at controlled delivery rates based on the patient's need, and in the case of drugs, the drug concentration being delivered.
Pumping systems offer advantages of mobility and positive control of flow rates by pump motor control. The prior art pumps include both peristaltic pumps and other positive displacement pumps. Both have the disadvantage of possible patient injury if an obstruction prevents free flow of liquid to the patient. Pumping pressure then increases until the obstruction clears or the equipment fails. The high pressure present upon sudden clearance of the obstruction can cause serious injury to the patient.